rostellum noun. [rɒ'stɛlǝm] Pl. -lla [-lǝ], -llums. In sense 1a formerly also Anglicized as rostel. M18.
[Latin = small beak or snout, dim. of ROSTRUM.]
1. Botany.
a. The radicle of a seed. M18-L19.
b. A beaklike process (a sterile stigma) in the column of an orchid flower between the fertile stigmas and the anther. M19.
2. Zoology.
a. The piercing mouthparts of a louse (now rare). Also, a projection on the male genitals of certain butterflies. E19.
b. The protruding forepart of the head of a tapeworm, armed with hooklets or spines. M19.

■ rostellar adjective pertaining to, or constituting, a rostellum L19.

■ rostellate ['rɒstǝleɪt, rɒ'stɛleɪt] adjective having a rostellum; of the form or shape of a rostellum: E19.

[TahlilGaran] English Dictionary ▲